Metal detector for detecting insertion of a surgical device into a hollow tube

ABSTRACT

Apparatus, systems, and methods for detecting the presence of a metallic surgical instrument. A metal detector for detecting insertion of a metallic surgical device into a hollow tube may include a switch, resonant circuit and a controller. The resonant circuit has a capacitor and a coil mounted to the hollow tube. The controller turn on the switch for a preselected time to temporarily provide a current to the resonant circuit and analyzes a resulting decaying voltage waveform originating from the resonant circuit when the switch is turned off in order to determine the presence and longitudinal depth of the metallic surgical device in the hollow tube.

TECHNICAL FIELD

The present invention relates to metal detectors, systems, and methods,and in particular, metal detectors for detecting a metallic surgicalinstrument.

BACKGROUND OF THE INVENTION

Conventional metal detectors use a power-consuming resonance circuitwhich is always turned on, and detects the change in electromagneticproperties, e.g., a Q value, of an inductor in the resonance circuit.When a piece of metal is near the resonance circuit, the metal detectorwill detect the change in Q-value to determine whether a metal has beenfound.

One problem with such a conventional metal detector is that because theresonant circuit is always on, the detector can waste a substantialamount of power. In the context of performing medical procedures using aportable robot, it is important to use as little power as possible.Therefore, there is a need to provide a device and method for moreefficiently detecting the presence of metal.

SUMMARY

According to one aspect of the present invention, a metal detector fordetecting insertion of a metallic surgical device into a hollow tube isprovided. The metal detector includes a switch, resonant circuit and acontroller. The resonant circuit includes a capacitor and a coilconnected to the capacitor in parallel. The coil is mounted to thehollow tube. The controller is adapted to turn on the switch for apreselected time to temporarily provide a current to the resonantcircuit and analyzes a resulting decaying voltage waveform originatingfrom the resonant circuit when the switch is turned off in order todetermine the presence of the metallic surgical device in the hollowtube.

According to another aspect of the present invention, a method ofdetecting insertion of a metallic surgical device into a hollow tube isprovided. Initially, a power supply is connected to a resonant circuithaving a capacitor and an inductor mounted to the hollow tube. After apreselected time period, the power supply is disconnected from theresonant circuit. Once the power supply is disconnected, the resonantcircuit generates a decaying waveform. The decaying waveform has adifferent shape depending on whether a metallic surgical device has beeninserted into the hollow tube or not. The presence of the metallicsurgical device in the hollow tube is then determined based on thegenerated decaying waveform.

By providing current to the resonant circuit for only a short period oftime, the present invention advantageously saves power. Moreover, theability to adjust the switch-on period allows for various pre-chargelevels of the inductor, or the volt-second product, or the flux.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of an automated medical system.

FIG. 2 illustrates an embodiment of a robot support system.

FIG. 3 illustrates an embodiment of a camera tracking system.

FIG. 4 illustrates an embodiment of a SCARA with end effector.

FIG. 5 illustrates an embodiment of a medical operation in which a robotsupport system and a camera system are disposed around a patient.

FIG. 6 illustrates an embodiment of an end effector.

FIG. 7 illustrates an embodiment of a cut away of an end effector.

FIG. 8 illustrates an embodiment of a perspective view of an endeffector cut away.

FIG. 9 illustrates an embodiment of a schematic of software architectureused in an automated medical system.

FIG. 10 illustrates an embodiment of a C-Arm imaging device.

FIG. 11 illustrates an embodiment of an imaging device.

FIG. 12 illustrates an embodiment of a gravity well for a medicalprocedure.

FIG. 13 illustrates an embodiment of an end effector tool moving towarda gravity well.

FIG. 14 illustrates an embodiment of an end effector tool positionedalong a gravity well.

FIG. 15 illustrates a portion of the end effector tool having a hollowtube and positioning of a coil in a metal detector according to oneaspect of the present invention.

FIG. 16 is a schematic diagram of a waveform generator according to anaspect of the present invention.

FIG. 17 is a schematic diagram of a controller for detecting a metalobject, such as an instrument positioned in the tube portion of the endeffector tool according to an aspect of the present invention.

FIG. 18 is an exemplary decaying waveform of the waveform generator.

FIG. 19 illustrates several decaying waveforms from the waveformgenerator which may represent the depth of insertion of the metal objectinto the hollow tube.

FIG. 20 is a graph of inductance values as a function of the first peakvoltage of several decaying waveforms.

FIG. 21 is a flowchart of a method of performing metal detection anddepth determination according to one aspect of the present invention.

FIG. 22 is a graph of Q values as a function of the depth of insertionof the metal object into the hollow tube.

DETAILED DESCRIPTION OF THE INVENTION

Briefly, the metal detection system of the present invention switches ona resonant circuit for a very short period of time to provide current tothe inductor positioned around the hollow tube and then analyzes theresulting decaying waveform once the current to the inductor is shutoff. The naturally oscillating decaying waveform can be analyzed todetect whether a metal object is inside the hollow tube. Moreover, thedecaying waveform can also be used to determine the depth of insertionof the metal object inside the hollow tube.

The present technique has several advantages over conventional methods.First, very little energy is required since a small initial energy isrequired to obtain a relatively high signal-to-noise ratio (SNR) andinductance sensitivity. Second, the initial energy is easily adjusted byadjusting the on-time of the switch SW1. This sets the initial flux inthe inductor L, which in turn, allows for variable sensitivities. Thiscan dynamically change any required inductive sensitivity, should theresonant circuit be in an electrically harsh environment. The frequencyof the excitation, or ringing of the coil, may also dynamically beadjusted so that more samples can be taken. These values can then beaveraged to obtain better SNR.

FIGS. 1-14 describe robotic systems that can incorporate the presentmetal detector which will be described with reference to FIGS. 15-22.

FIG. 1 illustrates an embodiment of an automated medical system 2. Priorto performance of an invasive medical procedure, a three-dimensional(“3D”) image scan may be taken of a desired surgical area of a patientand sent to a computer platform in communication with an automatedmedical system 2. In some embodiments, a physician may then program adesired point of insertion and trajectory for a surgical instrument toreach a desired anatomical target within or upon the body of thepatient. In some embodiments, the desired point of insertion andtrajectory may be planned on the 3D image scan, which in someembodiments, may be displayed on a display. In some embodiments, aphysician may plan the trajectory and desired insertion point (if any)on a computed tomography scan (hereinafter referred to as “CT scan”) ofthe patient. In some embodiments, the CT scan may be an isocentric C-armtype scan, or any other similar type scan, or intraoperative CT scan asis known in the art. However, in some embodiments, any known 3D imagescan may be used in accordance with the embodiments of automated medicalsystem 2.

A medical procedure may begin with automated medical system 2 movingfrom medical storage to a medical procedure room. Automated medicalsystem 2 may be maneuvered through doorways, halls, and elevators toreach a medical procedure room. Within the room, automated medicalsystem 2 may be physically separated into two separate and distinctsystems, a robot support system 4 and a camera tracking system 6. Robotsupport system 4 may be positioned adjacent the patient at any suitablelocation to properly assist medical personnel. Camera tracking system 6may be positioned at the base of the patient or any other locationsuitable to track movement of robot support system 4 and the patient.Robot support system 4 and camera tracking system 6 may be powered by anonboard power source and/or plugged into an external wall outlet.

Automated medical system 2, as illustrated in FIG. 1, may assistsurgeons and doctors during medical procedures. Automated medical system2 may assist surgeons and doctors by holding tools, aligning tools,using tools, guiding tools, and/or positioning tools for use. Inembodiments, as illustrated in FIG. 1, automated medical system 2 maycomprise of a robot support system 4 and a camera tracking system 6.Both systems may be coupled together by any suitable means. Suitablemeans may be, but are not limited to mechanical latches, ties, clamps,buttresses, magnetic and/or magnetic surfaces. The ability to combinerobot support system 4 and camera tracking system 6 may allow forautomated medical system 2 to maneuver and move as a single unit. Thiscombination may allow automated medical system 2 to have a smallfootprint in an area, allow easier movement through narrow passages andaround turns, and allow and storage within a smaller area.

Robot support system 4 may be used to assist a surgeon by orienting,positioning, holding and/or using tools during a medical procedure. Toproperly utilize, position, and/or hold tools, robot support system 4may rely on a plurality of motors, computers, and/or actuators tofunction properly. Illustrated in FIG. 1, robot body 8 may act as thestructure in which the plurality of motors, computers, and/or actuatorsmay be secured within robot support system 4. Robot body 8 may alsoprovide support for robot telescoping support arm 16. In embodiments,robot body 8 may be made of any suitable material. Suitable material maybe, but is not limited to, metal such as titanium, aluminum, orstainless steel, carbon fiber, fiberglass, or heavy-duty plastic. Thesize of robot body 8 may provide a solid platform on which othercomponents may connect and operate. Robot body 8 may house, conceal, andprotect the plurality of motors, computers, and/or actuators that mayoperate attached components.

Robot base 10 may act as a lower support for robot support system 4. Inembodiments, robot base 10 may support robot body 8 and may attach robotbody 8 to a plurality of powered wheels 12. This attachment to thewheels may allow robot body 8 to move in space efficiently. Robot base10 may run the length and width of robot body 8. Robot base 10 may beabout an two inches to about ten inches tall. Robot base 10 may be madeof any suitable material. Suitable material may be, but is not limitedto, metal such as titanium, aluminum, or stainless steel, carbon fiber,fiberglass, or heavy-duty plastic or resin. Robot base 10 may cover,protect, and support powered wheels 12.

In embodiments, as illustrated in FIG. 1, at least one powered wheel 12may be attached to robot base 10. Powered wheels 12 may attach to robotbase 10 at any location. Each individual powered wheel 12 may rotateabout a vertical axis in any direction. A motor may be disposed above,within, or adjacent to powered wheel 12. This motor may allow forautomated medical system 2 to maneuver into any location and stabilizeand/or level automated medical system 2. A rod, located within oradjacent to powered wheel 12, may be pressed into a surface by themotor. The rod, not pictured, may be made of any suitable metal to liftautomated medical system 2. Suitable metal may be, but is not limitedto, stainless steel, aluminum, or titanium. Additionally, the rod maycomprise at the contact surface-side end a buffer, not pictured, whichmay prevent the rod from slipping and/or create a suitable contactsurface. The material may be any suitable material to act as a buffer.Suitable material may be, but is not limited to, a plastic, neoprene,rubber, or textured metal. The rod may lift powered wheel 10, which maylift automated medical system 2, to any height required to level orotherwise fix the orientation of the automated medical system 2 inrelation to a patient. The weight of automated medial system 2,supported through small contact areas by the rod on each wheel, preventsautomated medical system 2 from moving during a medical procedure. Thisrigid positioning may prevent objects and/or people from movingautomated medical system 2 by accident.

Moving automated medical system 2 may be facilitated using robot railing14. Robot railing 14 provides a person with the ability to moveautomated medical system 2 without grasping robot body 8. As illustratedin FIG. 1, robot railing 14 may run the length of robot body 8, shorterthan robot body 8, and/or may run longer the length of robot body 8.Robot railing 14 may be made of any suitable material, but is notlimited to, metal such as titanium, aluminum, or stainless steel, carbonfiber, fiberglass, or heavy-duty plastic. Robot railing 14 may furtherprovide protection to robot body 8, preventing objects and or personnelfrom touching, hitting, or bumping into robot body 8.

Robot body 8 may provide support for a Selective Compliance ArticulatedRobot Arm, hereafter referred to as a “SCARA.” A SCARA 24 may bebeneficial to use within the automated medical system due to therepeatability and compactness of the robotic arm. The compactness of aSCARA may provide additional space within a medical procedure, which mayallow medical professionals to perform medical procedures free of excessclutter and confining areas. SCARA 24 may comprise robot telescopingsupport 16, robot support arm 18, and/or robot arm 20. Robot telescopingsupport 16 may be disposed along robot body 8. As illustrated in FIG. 1,robot telescoping support 16 may provide support for the SCARA 24 anddisplay 34. In embodiments, robot telescoping support 16 may extend andcontract in a vertical direction. Robot telescoping support 16 may bemade of any suitable material, but not limited to, metal such astitanium or stainless steel, carbon fiber, fiberglass, or heavy-dutyplastic. The body of robot telescoping support 16 may be any widthand/or height in which to support the stress and weight placed upon it.In embodiments, medical personnel may move SCARA 24 through a commandsubmitted by the medical personnel. The command may originate from inputreceived on display 34 and/or a tablet. The command may come from thedepression of a switch and/or the depression of a plurality of switches.Best illustrated in FIGS. 4 and 5, an activation assembly 60 maycomprise a switch and/or a plurality of switches. The activationassembly 60 may be operable to transmit a move command to the SCARA 24allowing an operator to manually manipulate the SCARA 24. When theswitch, or plurality of switches, is depressed the medical personnel mayhave the ability to move SCARA 24 easily. Additionally, when the SCARA24 is not receiving a command to move, the SCARA 24 may lock in place toprevent accidental movement by personnel and/or other objects. Bylocking in place, the SCARA 24 provides a solid platform upon which anend effector 22 and end effector tool 26 may be used during a medicaloperation.

Robot support arm 18 may be disposed on robot telescoping support 16 byany suitable means. Suitable means may be, but is not limited to, nutsand bolts, ball and socket fitting, press fitting, weld, adhesion,screws, rivets, clamps, latches and/or any combination thereof. Inembodiments, best seen in FIGS. 1 and 2, robot support arm 18 may rotatein any direction in regard to robot telescoping support 16. Robotsupport arm 18 may rotate three hundred and sixty degrees around robottelescoping support 16. Robot arm 20 may connect to robot support arm 18at any suitable location. Robot arm 20 may attach to robot support arm16 by any suitable means. Suitable means may be, but is not limited to,nuts and bolts, ball and socket fitting, press fitting, weld, adhesion,screws, rivets, clamps, latches and/or any combination thereof. Robotarm 20 may rotate in any direction in regards to robot support arm 18,in embodiments, robot arm 20 may rotate three hundred and sixty degreesin regards to robot support arm 18. This may allow an operator toposition robot arm 20 as desired.

End effector 22 may attach to robot arm 20 in any suitable location. Endeffector 22 may attach to robot arm 20 by any suitable means. Suitablemeans may be, but is not limited to, latch, clamp, nuts and bolts, balland socket fitting, press fitting, weld, screws, and/or any combinationthereof. End effector 22 may move in any direction in relation to robotarm 20. This may allow a user to move end effector 22 to a desired area.An end effector tool 26, as illustrated in FIG. 4 may attach to endeffector 22. End effector tool 26 may be any tool selected for a medicalprocedure. In some embodiments, the end effector tool 26 includes a tubeportion have a hollow tube 27 extending therethrough. The hollow tube 27is sized and configured to receive at least a portion of a surgicalinstrument. The hollow tube 27 is configured to be oriented by the robotarm 20 such that insertion and trajectory for the surgical instrument isable to reach a desired anatomical target within or upon the body of thepatient. The surgical instrument may include at least a portion of agenerally cylindrical instrument. By way of example, the surgicalinstrument may include one or more of a guide wire, cannula, aretractor, a drill, a reamer, a screw driver, an insertion tool, aremoval tool, or the like. Although the hollow tube 27 is generallyshown as having a cylindrical configuration, it will be appreciated bythose of skill in the art that the hollow tube 27 may have any suitableshape, size and configuration desired to accommodate the surgicalinstrument and access the surgical site. End effector tool 26 may bedisposed and removed from end effector 22. In embodiments, end effectortool 26 may have a dynamic reference array 52. Dynamic reference arrays52, herein referred to as “DRAs”, are rigid bodies which may be disposedon a patient and/or tool in a navigated surgical procedure. Theirpurpose may be to allow 3D localization systems to track the positionsof tracking markers that are embedded in the DRA 52, and thereby trackthe real-time position of relevant anatomy. Radio-opaque markers may beseen, recorded, and/or processed by camera 46. This tracking of 3Dcoordinates of tracking markers may allow automated medical system 2 tofind the DRA 52 in any space in relation to a patient 50.

As illustrated in FIG. 1, a light indicator 28 may be positioned on topof the SCARA 24. Light indicator 28 may illuminate as any type of lightto indicate “conditions” in which automated medical system 2 iscurrently operating. For example, the illumination of green may indicatethat all systems are normal. Illuminating red may indicate thatautomated medical system 2 is not operating normally. A pulsating lightmay mean automated medical system 2 is performing a function.Combinations of light and pulsation may create a nearly limitless amountof combinations in which to communicate the current operating“conditions.” In embodiments, the light may be produced by LED bulbs,which may form a ring around light indicator 28. Light indicator 28 maycomprise a fully permeable material that may let light shine through theentirety of light indicator 28. In embodiments, light indicator 28 mayonly allow a ring and/or designated sections of light indicator 28 toallow light to pass through.

Light indicator 28 may be attached to lower display support 30. Lowerdisplay support 30, as illustrated in FIG. 2 may allow an operator tomaneuver display 34 to any suitable location. Lower display support 30may attach to light indicator 28 by any suitable means. Suitable meansmay be but is not limited to, latch, clamp, nuts and bolts, ball andsocket fitting, press fitting, weld, adhesion, screws, rivets, and/orany combination thereof. In embodiments, lower display support 30 mayrotate about light indicator 28. In embodiments, lower display support30 may attach rigidly to light indicator 28. Light indicator 28 may thenrotate three hundred and sixty degrees about robot support arm 18. Lowerdisplay support 30 may be of any suitable length, a suitable length maybe about eight inches to about thirty four inches. Lower display support30 may act as a base for upper display support 32.

Upper display support 32 may attach to lower display support 30 by anysuitable means. Suitable means may be, but are not limited to, latch,clamp, nuts and bolts, ball and socket fitting, press fitting, weld,adhesion, screws, rivets, and/or any combination thereof. Upper displaysupport 32 may be of any suitable length, a suitable length may be abouteight inches to about thirty four inches. In embodiments, as illustratedin FIG. 1, upper display support 32 may allow display 34 to rotate threehundred and sixty degrees in relation to upper display support 32.Likewise, upper display support 32 may rotate three hundred and sixtydegrees in relation to lower display support 30.

Display 34 may be any device which may be supported by upper displaysupport 32. In embodiments, as illustrated in FIG. 2, display 34 mayproduce color and/or black and white images. The width of display 34 maybe about eight inches to about thirty inches wide. The height of display34 may be about six inches to about twenty two inches wide. The depth ofdisplay 34 may be about one half inch to about four inches.

In embodiments, a tablet may be used in conjunction with display 34and/or without display 34. In embodiments, the table may be disposed onupper display support 32, in place of display 34, and may be removablefrom upper display support 32 during a medical operation. In additionthe tablet may communicate with display 34. The table may be able toconnect to robot support system 4 by any suitable wireless and/or wiredconnection. In embodiments, the tablet may be able to program and/orcontrol automated medical system 2 during a medical operation. Whencontrolling automated medical system 2 with the tablet, all input andoutput commands may be duplicated on display 34. The use of a tablet mayallow an operator to manipulate robot support system 4 without having tomove around patient 50 and/or to robot support system 4.

As illustrated in FIG. 5, camera tracking system 6 may work inconjunction with robot support system 4. Described above, cameratracking system 6 and robot support system 4 may be able to attach toeach other. Camera tracking system 6, now referring to FIG. 1, maycomprise similar components of robot support system 4. For example,camera body 36 may provide the functionality found in robot body 8.Robot body 8 may provide the structure upon which camera 46 may bemounted. The structure within robot body 8 may also provide support forthe electronics, communication devices, and power supplies used tooperate camera tracking system 6. Camera body 36 may be made of the samematerial as robot body 8. Camera tracking system 6 may also communicatewith robot support system 4 by any suitable means. Suitable means maybe, but are not limited to, a wired or wireless connection.Additionally, camera tracking system 6 may communicate directly to thetable by a wireless and/or wired connection. This communication mayallow the tablet to control the functions of camera tracking system 6.

Camera body 36 may rest upon camera base 38. Camera base 38 may functionas robot base 10. In embodiments, as illustrated in FIG. 1, camera base38 may be wider than robot base 10. The width of camera base 38 mayallow for camera tracking system 6 to connect with robot support system4. As illustrated in FIG. 1, the width of camera base 38 may be largeenough to fit outside robot base 10. When camera tracking system 6 androbot support system 4 are connected, the additional width of camerabase 38 may allow automated medical system 2 additional maneuverabilityand support for automated medical system 2.

As with robot base 10, a plurality of powered wheels 12 may attach tocamera base 38. Powered wheel 12 may allow camera tracking system 6 tostabilize and level or set fixed orientation in regards to patient 50,similar to the operation of robot base 10 and powered wheels 12. Thisstabilization may prevent camera tracking system 6 from moving during amedical procedure and may keep camera 46 from losing track of DRA 52within a designated area. This stability and maintenance of tracking mayallow robot support system 4 to operate effectively with camera trackingsystem 6. Additionally, the wide camera base 38 may provide additionalsupport to camera tracking system 6. Specifically, a wide camera base 38may prevent camera tracking system 6 from tipping over when camera 46 isdisposed over a patient, as illustrated in FIG. 5. Without the widecamera base 38, the outstretched camera 46 may unbalance camera trackingsystem 6, which may result in camera tracking system 6 falling over.

Camera telescoping support 40 may support camera 46. In embodiments,telescoping support 40 may move camera 46 higher or lower in thevertical direction. Telescoping support 40 may be made of any suitablematerial in which to support camera 46. Suitable material may be, but isnot limited to, metal such as titanium, aluminum, or stainless steel,carbon fiber, fiberglass, or heavy-duty plastic. Camera handle 48 may beattached to camera telescoping support 40 at any suitable location.Cameral handle 48 may be any suitable handle configuration. A suitableconfiguration may be, but is not limited to, a bar, circular,triangular, square, and/or any combination thereof. As illustrated inFIG. 1, camera handle 48 may be triangular, allowing an operator to movecamera tracking system 6 into a desired position before a medicaloperation. In embodiments, camera handle 48 may be used to lower andraise camera telescoping support 40. Camera handle 48 may perform theraising and lowering of camera telescoping support 40 through thedepression of a button, switch, lever, and/or any combination thereof.

Lower camera support arm 42 may attach to camera telescoping support 40at any suitable location, in embodiments, as illustrated in FIG. 1,lower camera support arm 42 may rotate three hundred and sixty degreesaround telescoping support 40. This free rotation may allow an operatorto position camera 46 in any suitable location. Lower camera support arm42 may be made of any suitable material in which to support camera 46.Suitable material may be, but is not limited to, metal such as titanium,aluminum, or stainless steel, carbon fiber, fiberglass, or heavy-dutyplastic. Cross-section of lower camera support arm 42 may be anysuitable shape. Suitable cross-sectional shape may be, but is notlimited to, circle, square, rectangle, hexagon, octagon, or i-beam. Thecross-sectional length and width may be about one to ten inches. Lengthof the lower camera support arm may be about four inches to aboutthirty-six inches. Lower camera support arm 42 may connect totelescoping support 40 by any suitable means. Suitable means may be, butis not limited to, nuts and bolts, ball and socket fitting, pressfitting, weld, screws, and/or any combination thereof. Lower camerasupport arm 42 may be used to provide support for camera 46. Camera 46may be attached to lower camera support arm 42 by any suitable means.Suitable means may be, but is not limited to, nuts and bolts, ball andsocket fitting, press fitting, weld, screws, and/or any combinationthereof. Camera 46 may pivot in any direction at the attachment areabetween camera 46 and lower camera support arm 42. In embodiments acurved rail 44 may be disposed on lower camera support arm 42.

Curved rail 44 may be disposed at any suitable location on lower camerasupport arm 42. As illustrated in FIG. 3, curved rail 44 may attach tolower camera support arm 42 by any suitable means. Suitable means maybe, but are not limited to nuts and bolts, ball and socket fitting,press fitting, weld, adhesion, screws, rivets, clamps, latches, and/orany combination thereof. Curved rail 44 may be of any suitable shape, asuitable shape may be a crescent, circular, oval, elliptical and/or anycombination thereof. In embodiments, curved rail 44 may be anyappropriate length. An appropriate length may be about one foot to aboutsix feet. Camera 46 may be moveably disposed along curved rail 44.Camera 46 may attach to curved rail 44 by any suitable means. Suitablemeans may be, but are not limited to rollers, brackets, braces, motors,and/or any combination thereof. Motors and rollers, not illustrated, maybe used to move camera 46 along curved rail 44. As illustrated in FIG.3, during a medical procedure, if an object prevents camera 46 fromviewing one or more DRAs 52, the motors may move camera 46 along curvedrail 44 using rollers. This motorized movement may allow camera 46 tomove to a new position that is no longer obstructed by the objectwithout moving camera tracking system 6. While camera 46 is obstructedfrom viewing DRAs 52, camera tracking system 6 may send a stop signal torobot support system 4, display 34, and/or a tablet. The stop signal mayprevent SCARA 24 from moving until camera 46 has reacquired DRAs 52.This stoppage may prevent SCARA 24 and/or end effector 22 from movingand/or using medical tools without being tracked by automated medicalsystem 2.

End effector 22, as illustrated in FIG. 6, may be used to connectsurgical tools to robot support system 4. End effector 22 may comprise asaddle joint 62, an activation assembly 60, a load cell 64, and a toolconnection 66. Saddle joint 62 may attach end effector 22 to SCARA 24.Saddle joint 62 may be made of any suitable material. Suitable materialmay be, but is not limited to metal such as titanium, aluminum, orstainless steel, carbon fiber, fiberglass, or heavy-duty plastic. Saddlejoint 62 may be made of a single piece of metal which may provide endeffector with additional strength and durability. In examples saddlejoint 62 may attach to SCARA 24 by an attachment point 68. There may bea plurality of attachment points 68 disposed about saddle joint 62.Attachment points 68 may be sunk, flush, and/or disposed upon saddlejoint 62. In examples, screws, nuts and bolts, and/or any combinationthereof may pass through attachment point 68 and secure saddle joint 62to SCARA 24. The nuts and bolts may connect saddle joint 62 to a motor,not illustrated, within SCARA 24. The motor may move saddle joint 62 inany direction. The motor may further prevent saddle joint 62 from movingfrom accidental bumps and/or accidental touches by actively servoing atthe current location or passively by applying spring actuated brakes.Saddle joint 62 may provide the base upon which a load cell 64 and atool connection 66 may be disposed.

Load cell 64, as illustrated in FIGS. 7 and 8 may attach to saddle joint62 by any suitable means. Suitable means may be, but is not limited to,screws, nuts and bolts, threading, press fitting, and/or any combinationthereof. Load cell 64 may be any suitable instrument used to detect andmeasurement movement. In examples, load cell 64 may be a six axis loadcell, a three-axis load cell or a uniaxial load cell. Load cell 64 maybe used to track the force applied to end effector 22. As illustrated inFIG. 17, a schematic may show the communication between load cell 64 anda motor 120. In embodiments a load cell 64 may communicate with aplurality of motors 120. As load cell 64 senses pressure, information asto the amount of force applied may be distributed from a switch array122 and/or a plurality of switch arrays to a microcontroller unit 122.Microcontroller unit 124 may take the force information from load cell64 and process it with a switch algorithm. The switch algorithm mayallow microcontroller unit 124 to communicate with a motor driver 126. Amotor driver 126 may control the function of a motor 120, with whichmotor driver 126 may communicate with. Motor driver 126 may directspecific motors 120 to produce an equal amount of force measured by loadcell 64 through motor 120. In embodiments, the force produced may comefrom a plurality of motors 120, as directed by microcontroller unit 124.Additionally, motor driver 126 may receive input from motion controller128. Motion controller 128 may receive information from load cell 64 asto the direction of force sensed by load cell 64. Motion controller 128may process this information using a motion controller algorithm. Thealgorithm may be used to provide information to specific motor drivers126. To replicate the direction of force, motion controller 128 mayactivate and/or deactivate certain motor drivers 126. Working in unisonand/or separately, microcontroller unit 124 and motion controller 128may control motor 120 (or a plurality of motors 120) to induce in thedirection the motion and direction of force sensed by load cell 64. Thisforce-controlled motion may allow an operator to move SCARA 24 and endeffector 22 effortlessly and/or with very little resistance. Movement ofend effector 22 may position tool connection 66 in any suitable locationfor use by medical personnel.

Tool connection 66 may attach to load cell 64. Tool connection 66 maycomprise attachment points 68, a sensory button 70, tool guides 72,and/or tool connections 74. Best illustrated in FIGS. 6 and 8, there maybe a plurality of attachment points 68. Attachment points 68 may connecttool connection 66 to load cell 64. Attachment points 68 may be sunk,flush, and/or disposed upon tool connection 66. Connectors 76 may useattachment points 68 to attach tool connection 66 to load cell 64. Inexamples, connectors 76 may be screws, nuts and bolts, press fittings,and/or any combination thereof.

As illustrated in FIG. 6, a sensory button 70 may be disposed aboutcenter of tool connection 66. Sensory button 70 may be depressed when anend effector tool 26, best illustrated in FIG. 4, is connected to endeffector 22. Depression of sensory button 70 may alert robot supportsystem 4, and in turn medical personnel, that an end effector tool 26has been attached to end effector 22. As illustrated in FIG. 6, toolguides 72 may be used to facilitate proper attachment of end effectortool 26 to end effector 22. Tool guides 72 may be sunk, flush, and/ordisposed upon tool connection 66. In examples there may be a pluralityof tool guides 72 and may have any suitable patterns and may be orientedin any suitable direction. Tool guides 72 may be any suitable shape tofacilitate attachment of end effector tool 26 to end effector 22. Asuitable shape may be, but is not limited to, circular, oval, square,polyhedral, and/or any combination thereof. Additionally, tool guides 72may be cut with a bevel, straight, and/or any combination thereof.

Tool connection 66 may have attachment points 74. As illustrated in FIG.6, attachment points 74 may form a ledge and/or a plurality of ledges.Attachment points 74 may provide end effector tool 26 a surface uponwhich end effector tool 26 may clamp. In examples, attachment points 74may be disposed about any surface of tool connection 66 and oriented inany suitable manner in relation to tool connection 66.

Tool connection 66 may further serve as a platform for activationassembly 60. Activation assembly 60, best illustrated in FIGS. 6 and 8,may encircle tool connection 66. In embodiments, activation assembly 60may take the form of a bracelet. As bracelet, activation assembly 60 maywrap around tool connection 66. In embodiments, activation assembly 60,may be located in any suitable area within automated medical system 2.In examples, activation assembly 60 may be located on any part of SCARA24, any part of end effector 22, may be worn by medical personnel (andcommunicate wirelessly), and/or any combination thereof. Activationassembly 60 may be made of any suitable material. Suitable material maybe, but is not limited to neoprene, plastic, rugger, gel, carbon fiber,fabric and/or any combination thereof. Activation assembly 60 maycomprise of a primary button 78 and a secondary button 80. Primarybutton 78 and secondary button 80 may encircle the entirety of toolconnection 66. Primary button 78 may be a single ridge, as illustratedin FIG. 6, which may encircle tool connection 66. In examples, primarybutton 78 may be disposed upon activation assembly 60 along the endfarthest away from saddle joint 62. Primary button 78 may be disposedupon primary activation switch 82, best illustrated on FIG. 7. Primaryactivation switch 82 may be disposed between tool connection 66 andactivation assembly 60. In examples, there may be a plurality of primaryactivation switches 82, which may be disposed adjacent and beneathprimary button 78 along the entire length of primary button 78.Depressing primary button 78 upon primary activation switch 82 may allowan operator to move SCARA 24 and end effector 22. As discussed above,once set in place, SCARA 24 and end effector 22 may not move until anoperator programs robot support system 4 to move SCARA 24 and endeffector 22, or is moved using primary button 78 and primary activationswitch 82. In examples, it may require the depression of at least twonon-adjacent primary activation switches 82 before SCARA 24 and endeffector 22 will respond to commands. Depression of at least two primaryactivation switches 82 may prevent the accidental movement of SCARA 24and end effector 22 during a medical procedure.

Activated by primary button 78 and primary activation switch 82, loadcell 64 may measure the force magnitude and/or direction of forceexerted upon end effector 22 by medical personnel. This information maybe transferred to motors within SCARA 24 that may be used to move SCARA24 and end effector 22. Information as to the magnitude and direction offorce measured by load cell 64 may cause the motors to move SCARA 24 andend effector 22 in the same direction as sensed by load cell 64. Thisforce controlled movement may allow the operator to move SCARA 24 andend effector 22 easily and without large amounts of exertion due to themotors moving SCARA 24 and end effector 22 at the same time the operatoris moving SCARA 24 and end effector 22.

Secondary button 80, as illustrated in FIG. 6, may be disposed upon theend of activation assembly 60 closest to saddle joint 62. In examplessecondary button 80 may comprise a plurality of ridges. The plurality ofridges may be disposed adjacent to each other and may encircle toolconnection 66. Additionally, secondary button 80 may be disposed uponsecondary activation switch 84. Secondary activation switch 84, asillustrated in FIG. 7, may be disposed between secondary button 80 andtool connection 66. In examples, secondary button 80 may be used by anoperator as a “selection” device. During a medical operation, robotsupport system 4 may notify medical personnel to certain conditions bydisplay 34 and/or light indicator 28. Medical personnel may be promptedby robot support system 4 to select a function, mode, and/or asses thecondition of automated medical system 2. Depressing secondary button 80upon secondary activation switch 84 a single time may activate certainfunctions, modes, and/or acknowledge information communicated to medicalpersonnel through display 34 and/or light indicator 28. Additionally,depressing secondary button 80 upon secondary activation switch 84multiple times in rapid succession may activate additional functions,modes, and/or select information communicated to medical personnelthrough display 34 and/or light indicator 28. In examples, at least twonon-adjacent secondary activation switches 84 may be depressed beforesecondary button 80 may function properly. This requirement may preventunintended use of secondary button 80 from accidental bumping by medicalpersonnel upon activation assembly 60. Primary button 78 and secondarybutton 80 may use software architecture 86 to communicate commands ofmedical personnel to automated medical system 2.

FIG. 9 illustrates a flow chart of software architecture 86 which may beused within automated medical system 2. Software architecture 86 may beused to automated robot support system 4 and camera tracking system 6.Additionally, software architecture 86 may allow an operator tomanipulate automated medical system 2 based upon commands given from theoperator. In examples, operator commands may comprise Picture Archivaland Communication Systems (PACS) 88 (which may communicate withautomated imaging system 104, discussed below), USB Devices 90, andcommands from tablet 54. These operator commands may be received andtransferred throughout automated medical system 2 by a computerprocessor 92. Computer processor 92 may be able to receive all commandsand manipulate automated medical system 2 accordingly. In examples,computer processor 92 may be able to control and identify the locationof individual parts that comprise automated medical system 2.Communicating with camera tracking system 6 and display 34, computerprocessor 92 may be able to locate a patient, end effector 22, and robotsupport system 4 in a defined space (e.g., illustrated in FIG. 5).Additionally, computer processor 92 may be able to use commands fromdisplay 34 and camera tracking system 6 to alter the positions of SCARA24. Information from load cell 64, based upon measured force magnitudeand direction, may be processed by computer processor 92 and sent tomotors within SCARA 24, as discussed above. A General Algebraic ModelingSystem (GAMS) 94 may translate information regarding force magnitudefrom load cell 64 to electronic signals which may be useable by computerprocessor 92. This translation may allow computer processor 92 to trackthe location and movement of robot support system 4 in a defined spacewhen SCARA 24 and end effector 22 are moving. Computer processor 92 mayfurther use firmware 96 to control commands and signals from robot body8. Firmware 96 may comprise commands that are hardwired to automatedmedical system 2. For example, computer processor 92 may require powerfrom power supply 98 to operate. Firmware 96 may control thedistribution of power from power supply 98 to automated medical system2. Additionally, computer processor 92 may control firmware 96 and thepower distribution based on operator commands. In examples, firmware 96may communicate with light indicator 28, powered wheels 12, and platforminterface 100. Platform interface 100 may be a series of hardwiredbutton commands that directly control automated medical system 2.Buttons commands are not limited to but may comprise functions that maymove automated medical system 2 in any direction, initiate an emergencystop, initiate movement of SCARA 24, and/or communicate current systemfunctionality to medical personnel. Computer processor 92 may processand distribute all operator commends to perform programmed tasks bymedical personnel.

Automated imaging system 104 may be used in conjunction with automatedmedical system 2 to acquire pre-operative, intra-operative,post-operative, and/or real-time image data of patient 50. Anyappropriate subject matter may be imaged for any appropriate procedureusing automated imaging system 104. In embodiments, automated imagingsystem 104 may be an any imaging device such as imaging device 106and/or a C-arm 108 device. It may be desirable to take x-rays of patient50 from a number of different positions, without the need for frequentmanual repositioning of patient 50 which may be required in an x-raysystem. C-arm 108 x-ray diagnostic equipment may solve the problems offrequent manual repositioning and may be well known in the medical artof surgical and other interventional procedures. As illustrated in FIG.10, a C-arm 108 may comprise an elongated C-shaped member 110terminating in opposing distal ends 112 of the “C” shape. C-shapedmember 110 may further comprise an x-ray source 114 and an imagereceptor 116, which may be mounted at or near distal ends 112,respectively, of C-arm 108 in opposing orientation, with C-arm 108supported in a suspended position. The space within C-arm 108 of the armmay provide room for the physician to attend to the patientsubstantially free of interference from x-ray support structure 118.X-ray support structure 118 may rest upon wheels 120, which may enableC-arm 108 to be wheeled from room to room and further along the lengthof patient 50 during a medical procedure. X-ray images produced fromC-arm 108 may be used in an operating room environment to help ensurethat automated medial system 2 may be properly positioned during amedical procedure.

C-arm 108 may be mounted to enable rotational movement of the arm in twodegrees of freedom, (i.e. about two perpendicular axes in a sphericalmotion). C-arm 108 may be slidably mounted to x-ray support structure118, which may allow orbiting rotational movement of C-arm 108 about itscenter of curvature, which may permit selective orientation of x-raysource 114 and image receptor 116 vertically and/or horizontally. C-arm108 may also be laterally rotatable, (i.e. in a perpendicular directionrelative to the orbiting direction to enable selectively adjustablepositioning of x-ray source 114 and image receptor 116 relative to boththe width and length of patient 50). Spherically rotational aspects ofC-arm 108 apparatus may allow physicians to take x-rays of patient 50 atan optimal angle as determined with respect to the particular anatomicalcondition being imaged. In embodiments a C-arm 108 may be supported on awheeled support cart 120. In embodiments imaging device 106 may be usedseparately and/or in conjunction with C-arm 108.

An imaging device 106, as illustrated in FIG. 11, may comprise a gantryhousing 124, which may enclose an image capturing portion, notillustrated. The image capturing portion may include an x-ray sourceand/or emission portion and an x-ray receiving and/or image receivingportion, which may be disposed about one hundred and eighty degrees fromeach other and mounted on a rotor (not illustrated) relative to a trackof the image capturing portion. The image capturing portion may beoperable to rotate three hundred and sixty degrees during imageacquisition. The image capturing portion may rotate around a centralpoint and/or axis, allowing image data of patient 50 to be acquired frommultiple directions or in multiple planes.

In embodiments imaging device 106 may comprises a gantry housing 124having a central opening 126 for positioning around an object to beimaged, a source of radiation that is rotatable around the interior ofgantry housing 124, which may be adapted to project radiation from aplurality of different projection angles. A detector system may beadapted to detect the radiation at each projection angle to acquireobject images from multiple projection planes in a quasi-simultaneousmanner. In embodiments, a gantry may be attached to a support structureimaging device support structure 128, such as a wheeled mobile cart 130with wheels 132, in a cantilevered fashion. A positioning unit 134 maytranslate and/or tilt the gantry to a desired position and orientation,preferably under control of a computerized motion control system. Thegantry may include a source and detector disposed opposite one anotheron the gantry. The source and detector may be secured to a motorizedrotor, which may rotate the source and detector around the interior ofthe gantry in coordination with one another. The source may be pulsed atmultiple positions and orientations over a partial and/or full threehundred and sixty degree rotation for multi-planar imaging of a targetedobject located inside the gantry. The gantry may further comprise a railand bearing system for guiding the rotor as it rotates, which may carrythe source and detector. Both and/or either imaging device 106 and C-arm108 may be used as automated imaging system 104 to scan patient 50 andsend information to automated medical system 2.

Automated imaging system 104 may communicate with automated medicalsystem 2 before, during, and/or after imaging has taken place.Communication may be performed through hard wire connections and/orwireless connections. Imaging may be produced and sent to automatedmedical system 2 in real time. Images captured by automated imagingsystem 104 may be displayed on display 34, which may allow medicalpersonal to locate bone and organs within a patient. This may furtherallow medical personnel to program automated medial system 2 to assistduring a medical operation.

During a medical operation, medical personnel may program robot supportsystem 4 to operate within defined specifications. For examples, asillustrated in FIG. 12, a patient 50 may have a medical procedureperformed upon the spine. Medical personnel may use imaging equipment tolocate and find the spine, as detailed above. Using the images, anoperator may upload the information regarding the location of the spineinto automated medical system 2. Automated medical system 2 may thentrack, locate, and move end effector tools 26 to areas specified by theoperator. In an example, a gravity well 102 and/or a plurality ofgravity wells 102 may be mapped onto the spine of patient 50, asillustrated in FIG. 12. Gravity wells 102 may be areas, programmed by anoperator, to attract end effector tools 26. These areas may cause SCARA24 and end effector 22 to move toward the direction, angle, and locationprogrammed by medical personnel.

As illustrated in FIG. 13, a gravity well 102 indicates, in a virtualspace, the angle and location end effector tool 26 may need to bepositioned for a medical procedure. End effector tool 26, asillustrated, may be moved by an operator using activation assembly 60,discussed above. As end effector tool 26 moves within the area ofgravity well 102, the operator may feel the motors in SCARA 24 being tomove end effector tool 26 into the programmed position of gravity well102. As illustrated in FIG. 14, gravity well 102 may maneuver endeffector tool 26 into the programmed position. In an example, if theoperator begins to move end effector tool 26 using activation assembly60, the operator may feel the motors provide resistance against themovement. The resistance from the motors may not be strong enoughresistance to keep end effector tool 26 within gravity well 102. Thismay be beneficial as it may allow the operator to maneuver end effectortool 26 to additional gravity wells 102. Gravity well 102 may beprogrammed into automated medical system 2 before the medical operationand/or during the medical operation. This may allow medical personnel tomove a gravity well 102 based on the changing conditions of the medicalprocedure. Gravity wells 102 may allow automated medical system 2 toplace end effector tools 26 in the required area quickly, easily, andcorrectly.

FIG. 15 illustrates a portion of the robot's end effector 22 includingthe tool portion 26 defining hollow tube 202. In a robot-assistedsurgery, a metal object, such as a metallic surgical instrument 204, isinserted into the hollow tube 202. The hollow tube 202 is sized andconfigured to receive at least a portion of the metallic surgicalinstrument 204. The metal object may include any suitable surgicalinstrument 204 known in the art including, but not limited to, a guidewire, a cannula, a retractor, a drill, a reamer, a driver, an insertiontool, a removal tool, or the like. Although the hollow tube 202 isgenerally shown as having a cylindrical configuration, it will beappreciated by those of skill in the art that the hollow tube 202 mayhave any suitable shape, size and configuration desired to accommodatethe surgical instrument 204 and access the surgical site.

Before the surgical procedure takes place, the hollow tube 202 isconfigured to be aligned and/or oriented by the robot arm 20 such thatinsertion and/or trajectory for the surgical instrument 204 is able toreach a desired anatomical target within or upon the body of thepatient. Thus, the surgical instrument 204 may be inserted into thehollow tube 202 after operating the robot 4 to achieve this desiredalignment and/or orientation for the desired surgical procedure.Preferably, the robotic system is shut down once the metal surgicalinstrument 204 is inserted through a portion of the hollow tube 202 orthrough the entire hollow tube 202. Thus, when the metallic surgicalinstrument 204 is inserted into the tube 202, the presence of theinstrument 204 and/or insertion of the instrument 204 should be detectedin order to shut off one or more electronic components of the robot 4,such as cameras, infrared detectors, or the like for safety reasons.This safety mechanism ensures that the robot 4, in particular, the robotarm 20, and more particularly, end effector 22, does not move when themetallic surgical instrument 204 is present in the end effector 22.Thus, this automatic shut off system ensures the safety of the patientbecause the trajectory and orientation of the surgical instrument 204positioned through tube 202 cannot change during the operation.

In order to detect the presence of a metallic surgical instrument 204within the tube 202, a sensor may be used. For example, the sensor maybe in the form of an inductor coil 206. As shown in FIG. 15, an inductorcoil 206 is positioned around the hollow tube 204. The inductor coil 206may be positioned either inside or outside of the tube 204. In addition,the inductor coil 206 may be positioned at a suitable location along thelength of the tube 202. For example, the coil 206 may be positionedsubstantially at the longitudinal center of the tube 202. It may beappreciated that the coil 206 may be positioned at another locationalong the length of the tube 202, e.g., proximate the distal or proximalend.

FIG. 16 is a schematic diagram of a decaying waveform generator 208according to an aspect of the present invention. A capacitor 210connected in parallel with the inductor 206 define a resonance circuitof the generator 208. A voltage source Vs provides current to theresonance circuit through a current limiting resistor R1 which isconnected in series with a switch SW1. A second resistor R2 is connectedbetween the resonant circuit and an output terminal Vout.

A first clamp diode D1 has an anode connected to ground and a cathodeconnected to the output terminal Vout. A second clamp diode D2 has ananode connected to the output terminal Vout and a cathode connected to areference voltage source Vcmp. The switch SW1 is under the control of acontroller 240 as shown in FIG. 17.

Briefly, in operation, when the controller 240 turns on the switch SW1for a predetermined time period τ, the switch SW1 connects the voltagesource Vs to the resonant circuit (206, 210) to allow current from thevoltage source Vs to flow into the coil 206 and place an initial voltageVc across the capacitor 210. This action also sets the initial charge inthe inductor L to a value (Vs·τ), where τ is the switch on time.

When the controller 240 turns off the switch SW1, the voltage source Vsis disconnected from the resonant circuit (206, 210) and the voltageacross the capacitor 210 starts to oscillate in a decaying manner. Theresistor R2 sets the current being provided to the output terminal Vo.The clamping diode D1 ensures that the voltage at the output terminalVout does not fall substantially below ground. If the capacitor 210tries to pull the output voltage below zero, the diode D1 turns on andforces the output terminal Vout to ground voltage less the forwardbiasing voltage (e.g., 0.3 V) of the diode such that the minimum voltageat the output terminal Vout is −0.3 Volt. In effect, the clamping diodeD1 acts as a rectifier to provide only a positive voltage to the outputterminal Vout.

If, on the other hand, the voltage at the output terminal Vout tries togo above the reference voltage Vcmp, the clamping diode D2 turns on andclamps the output voltage to Vcmp plus the forward biasing voltage(e.g., 0.3 V) of the diode. The reference voltage Vcmp can be set to themaximum voltage permissible (e.g., 5 V) for the controller 240 to makethe waveform generator 208 suitable for any number of microcontrollerunits on the market. Thus, the maximum voltage at the output terminalVout is 5.3 Volt.

In case the controller 240 fails to turn off the switch SW1, e.g., thecontroller 240 becomes frozen, the current limiting resistor R1 (e.g.,330 Ohms) ensures that the coil 206 does not become damaged.

Immediately after the switch SW1 is turned off, the resulting decayingwaveform at the output terminal Vout is stored in the controller 240.The stored decaying waveform can then be analyzed to determine theeffective Q-value of the resonant circuit. In the present configuration,the Q value of the circuit is

${= \frac{\sqrt{L/C}}{ESR}},$where ESR is the coils “Effective Series Resistance”. The Q value canchange depending on both the inductance of the coil, and its ESR, and itis this change in Q that is responsible for the change in decay of thewaveform. The effective Q value can be used to determine the presence ofa metal object 204 inside the hollow tube 202 and the depth of insertionto determine, for example, whether the metal object has been fullyinserted as will be explained in more detail below.

FIG. 17 is a schematic diagram of a controller 240 for detecting thepresence of or insertion of a metal object 204 in tube 202 according toan aspect of the present invention.

The controller 240 of the present invention is connected to the outputterminal Vout and switch SW1 through a communication link 252 which isconnected to an I/O interface 242, which receives information from andsends information over the communication link 252. The controller 240includes memory storage 244 such as RAM (random access memory),processor (CPU) 246, program storage 248 such as FPGA, ROM or EEPROM,and data storage 250 such as a hard disk, all commonly connected to eachother through a bus 253. The program storage 248 stores, among others,metal detection module 254 containing software to be executed by theprocessor 246.

The metal detection module 254 executed by the processor 246 controlsthe switch SW1. The module 254 can also control the inductor 206 andcapacitor 210 if variable inductor or capacitor were used in order tocontrol the frequency of the decaying waveform.

The metal detection module 254 includes a user interface module thatinteracts with the user through the display device 211 and input devicessuch as keyboard 212 and pointing device 214 such as arrow keys, mouseor track ball. The user interface module assists the user in programmingthe programmable components in the waveform generator 208 andcalibration of data as will be explained in more detail herein. Any ofthe software program modules in the program storage 248 and data fromthe data storage 250 can be transferred to the memory 244 as needed andis executed by the CPU 246.

An analog-to-digital (A/D) converter 243 is connected to the I/Ointerface 242. The A/D converter 243 converts the analog decayingwaveform at the output terminal Vout into digital data to be stored inthe storage 250 by the processor 246.

One exemplary controller 240 may be 8051 microcontroller from IntelCorporation of Santa Clara, Calif. However, any processor ormicrocontroller that offers an A/D converter can be used.

In one embodiment, parts of or the entire the controller 240 includingthe input devices 212, 214 and display device 211 can be incorporatedinto the automated medical system 2 of FIG. 1. For example, the display211 can be the same as display 34.

A method of performing metal detection and/or depth determination (e.g.,of surgical instrument 204) by the metal detection module 254 will nowbe explained with reference to FIG. 21. In step 256, the user interfaceof the metal detection module 254 interacts with the user in selectingthe switch-on time τ, metal detection calculation method, andcalibration mode, which are stored in the data storage 250. If the useror the module 254 itself selects the calibration mode, then all of thesteps are used to determine an initial Q value (and initial inductancevalue) without any metal object for storage in the storage 250 for lateruse in determining the presence and depth of the metal object 204 insidethe hollow tube 202.

In step 258, the controller 240 sends a signal through the link 252 toturn on the switch SW1 for a preselected time (e.g., 100 microseconds).The switch SW1 connects the voltage source Vs to the resonant circuit(6,10) and current I_(e) flows through R1. This places an initialvoltage Vs across the capacitor 210, and pre-charges the coil 206 to aninitial flux level of (Vs·τ). This magnetic charge is then built up inthe coil 206 until the switch SW1 turns off. Once the switch SW1 turnsoff, the resonating current in the resonant circuit outputs a decayingwaveform.

In step 260, the decaying waveform at the output terminal Vout isconverted into digital data and stored in the storage 250.

In step 262, a Q value of the inductor 206 is calculated by thefollowing methods.

The initial current in the coil 206 may be set by two different methods.The first method is by keeping the switch SW1 closed for a sufficientlylong time, allowing I_(e) to settle to

$\frac{v}{\left( {{R\; 1} + {ESR}} \right)}.$

The other method is to keep the switch SW1 on for a “short time” τsetting the initial current to

${\frac{v}{L} \cdot \tau},$where L is the inductance of the coil 206.

After such initial current is established in the coil 206 and initialvoltage across the capacitor 210, SW1 opens and the circuit is allowedto resonate at its own natural frequency as a decaying voltage waveformat the capacitor 210. The voltage across the capacitor 210 may bemonitored to calculate what the Q value of the coil 206 is. Therelationship between the time domain voltage across the capacitor(V_(c)(t)) and the coil's inductance L is realized in equation 1:

$\begin{matrix}{{V_{c}(t)} = {\frac{v \cdot \omega_{0}^{2} \cdot e^{{- \gamma} \cdot t}}{\gamma^{2} + \omega_{n}^{2}} \cdot {\quad\left\lbrack {{{\left( {\gamma - {\tau \cdot \gamma^{2}} - {\tau \cdot \omega_{n}^{2}}} \right) \cdot \sin}\;\left( {\omega_{n} \cdot t} \right)} + \left. \quad{{\omega_{n} \cdot \cos}\;\left( {\omega_{n} \cdot t} \right)} \right\rbrack - {v \cdot \frac{\omega_{0}^{2} - \gamma^{2} - \omega_{n}^{2}}{\gamma^{2} + \omega_{n}^{2}}}} \right.}}} & (1) \\{Where} & \; \\{{\gamma = {\frac{1}{2} \cdot \frac{R_{ESR}}{L}}},{\omega_{0} = \frac{1}{\sqrt{L \cdot C}}},{\omega_{n} = \sqrt{\omega_{0}^{2} - \gamma^{2}}}} & \;\end{matrix}$

-   -   ν=source voltage Vs,    -   ω₀=natural undamped resonant frequency of coil 206 and capacitor        210,    -   γ=damping coefficient of coil 206 and capacitor 210, which        includes the ESR (Effective Series Resistance) of the coil,    -   τ=on time of the switch SW1, and    -   ω_(n)=natural resonant frequency.        Note that γ defined above contains both the ESR and the coil's        inductance L, and is therefore directly related to the Q value.        The relationship is:

$\begin{matrix}{Q = {\frac{1}{\omega_{0}} \cdot \frac{1}{2 \cdot \gamma}}} & (2)\end{matrix}$

The voltage across the capacitor 210 produces a current in R2 and atypical waveform produced at the output terminal Vout is shown in FIG.18. At t=0, the switch SW1 shuts off. As shown in FIG. 18, only thefirst three waves (t2 to t4, t5 to t7 and t8 to t10) in the waveform areshown. The waveform has a first peak voltage at t=t3, second peak att=t6 and third peak at t=t9.

The decaying waveform may be used in many ways to calculate what the Qvalue of the coil 206 is. A first method to determine the Q value is tomeasure the “average value” of the waveform. An average value can berealized by calculating the integral of the area under the waveform overa predetermined number of waves or time period and then dividing by thetime interval where the voltage is present. A relationship between theaverage value and Q value can be determined empirically or by equation(1).

Another way to determine the Q value is to measure one or more of thepeak voltages Vout1, Vout2 and Vout3 and their corresponding times t3,t6 and t9. For example, the voltage value at the first peak (i.e., Vout1in FIG. 17) and t=t3 can be determined. From these values, the Q valuemay be computed from equation (1).

Another way to determine the Q value is to measure the zero crossingvoltages that occur at times t2, t4, t5, t7, t8 and t10. From thesevalues, the Q value may be computed from equation (1).

Yet another way to determine the Q value is to measure the signal energyof the waveform over a time “window” by computing the integral of thewaveform in the time t₀-t_(n), such that t₀>3τ where τ is the timeconstant of the resonant circuit. From these values, the Q value may becomputed from equation (1).

Among those described above, one exemplary embodiment uses the fourthmethod of integrating over a time window. As the waveform signal issampled by the A/D converter 243 over some time t, the metal detectionmodule 254 of the controller 240 can compute a sum of the sampledsignals as a way to integrate the signal. That sum can be compared orcharacterized to different values of Q by equation (1) above orempirically. The characterization can be stored in storage as a lookuptable which can then be retrieved and used by the metal detection module254 with interpolation.

In step 264, the metal detection module 254 determines whether the metalobject 204 is present in the hollow tube 202. As an example, in oneembodiment, assume that the user has selected the first peak voltagedetermination as the method of obtaining a Q value in step 256. Once theQ value has been obtained from the first peak voltage and t3 values, themetal detection module 254 compares it to a threshold value which hasbeen preselected.

In some cases, the ESR doesn't change much. If this is the case, the Qvalue is purely a function of the inductance only. FIG. 20 shows a graphof the computed inductance values vs. the voltage values at the firstpeak value (i.e., Vout1 at t=t3 in FIG. 17) once the initial voltage att=0 falls to ground. Based on the graph, the threshold inductance valuecan be set at 50 μH below which the metal detection module 254 considersthe metal object to be present (e.g., metal object is substantiallyfully inserted into the tube 202). Alternatively, the graph of FIG. 20can be converted to a graph of Q values vs. first peak voltage and aQ-value threshold value equivalent to L=50 μH can be stored as thethreshold Q value.

Another way to detect the presence is to empirically obtain a thresholdQ value (or inductance value) under which the module 254 determines thatthe metal object 204 is present in the hollow tube 202. This can be doneby inserting the metal object 204 into the hollow tube 202 at auser-selected depth and determining the Q value (or inductance value)based on a decaying waveform.

In step 266, the metal detection module 254 determines how deep themetal object 204 is inside the hollow tube 202. One way to determine thedepth is to empirically obtain a lookup table of Q values (or inductancevalues) at various depths for a given metal object 204.

FIG. 19 illustrates several decaying waveforms from the waveformgenerator 208 which represent the depth of insertion of the metal object204 into the hollow tube 202. Waveform 270 represents one in which nometal object is present. Waveform 270 equates to the original Q value ofQ1 without any metal object insertion. Waveform 272 represent one inwhich the metal object 204 has been inserted half way, i.e., the distalend of the metal object 204 is at a midpoint between the center of thetube 202 and proximal end of the tube. Waveform 72 equates to Q value ofQ2 which is less than Q1. Waveform 274 represent one in which the metalobject 204 has been inserted fully, i.e., the distal end of the metalobject 204 is at the center of the coil 206. Waveform 274 equates to Qvalue of Q3 which is less than Q2. Thus, the insertion depth of themetal object 204 is negatively correlated to the Q value.

Based on such empirical data, a lookup table can be prepared. The tableequates various Q values to respective distance Δx (i.e., depth). Oncethe table is obtained, it is stored in the storage 250 and is used bythe metal detection module 254 to obtain the depth of insertion of themetal object 204 based on the Q value from step 262.

Another example of a lookup table is shown in FIG. 22. FIG. 22 shows agraph of Q values as a function of the depth of insertion of the metalobject into the hollow tube (distance Δx). The experiment was performedwith a 6 mm diameter Ferrite metal object (cylinder) and a 15 mmdiameter by 8 mm length coil. The distance Δx represents the distancefrom the distal end of the metal cylinder and the center of the coil. Ascan be seen, as the metal cylinder 204 is inserted into the hollow tube202, the Q value changes. The graph of FIG. 22 can be stored in thestorage 250 as a lookup table for retrieval by the metal detectionmodule 254. Interpolation may need to be used if the lookup table isstored as a set of discrete points, rather than an equation.

In step 266, the metal detection module 254 looks up the depth valuefrom the lookup table stored in the storage 250 for a given Q valuewhich was found in step 262. The depth value from the lookup table isgenerated as the output from the metal detection module 254.

In the embodiment shown, a rectified decaying waveform has been usedbecause it is relatively simple to integrate over the waveform. If afull non-rectified decaying waveform is used, more components will beneeded as a simple method of integrating will not work because of thesymmetry of the waves.

Although the present invention has been described above with the coilwhich is positioned at the center of the tube 202, it is possible toposition the coil at the proximal end, distal end or anywhere along thetube. It is also possible to use multiple coils that are spaced apart.For example, three coils (respectively positioned at the proximal end,center and distal end) that are uniformly spaced from each other can beused to detect the presence and depth of the metal object inside thehollow tube 202. As can be appreciated, this embodiment can beparticularly useful when determining the depth of the metal object(e.g., surgical instrument 204) in the hollow tube 202. If multiplecoils are used, it is preferable to separate the on time of the switchSW1 for each inductor coil (e.g., turning on and off the resonantcircuit and measuring the inductance value prior to turning on the nextresonant circuit) so as to prevent one resonant circuit from interferingwith another.

Advantageously, the present invention uses minimum number of componentsby utilizing the power of a processor such as a microcontroller for theprocessing of waveforms. The circuit in the form of a waveform generator208 requires only the switch SW1, capacitor 210 and inductor 206.

Accordingly, before the surgical procedure takes place, the hollow tube202 is aligned and/or oriented by the robot 4 in order to obtain adesired insertion angle and/or trajectory for the surgical instrument204. After properly positioned, the surgical instrument 204 may beinserted into the hollow tube 202. In order to ensure the desiredalignment, the robotic system is shut down by the presence of thesurgical instrument 204 in the tube 202 or at a certain depth therein.Thus, when the surgical instrument 204 is inserted into the tube 202,the mere presence of the instrument 204 triggers an automatic shut offof certain robotic components (e.g., those the control or allow formovement of the robotic arm 20. This automatic shut off ensures thetrajectory and orientation of the surgical instrument 204, and thuscannot change during the operation. In order to move, the robot arm 20,the instrument 204 must be removed from the tube 202, thereby ensuringsafety of the patient.

Although the invention has been described in detail and with referenceto specific embodiments, it will be apparent to one skilled in the artthat various changes and modifications can be made without departingfrom the spirit and scope of the invention. Thus, it is intended thatthe invention covers the modifications and variations of this inventionprovided they come within the scope of the appended claims and theirequivalents. It is expressly intended, for example, that all rangesbroadly recited in this document include within their scope all narrowerranges which fall within the broader ranges. It is also intended thatthe components of the various devices disclosed above may be combined ormodified in any suitable configuration.

What is claimed is:
 1. A metal detector for detecting insertion of ametallic surgical device into a hollow tube, comprising: a coil mountedto the hollow tube; a capacitor coupled in parallel to and defining aresonant circuit with the coil; a switch adapted to couple a voltagesource to the resonant circuit; a controller connected to the switch andthe resonant circuit, and operable to turn on the switch for apreselected time period to temporarily provide a current to the resonantcircuit to charge the capacitor to a selected initial voltage andanalyze a decaying voltage waveform originating from the resonantcircuit when the switch is turned off to determine a presence of themetallic surgical device in the hollow tube; wherein the hollow tube iscoupled to an end effector of a robotic system, wherein when themetallic surgical instrument is detected within the hollow tube, thecontroller prevents the end effector from moving, thereby causing atrajectory and orientation of the metallic surgical device to be fixedthrough the hollow tube during a surgical procedure.
 2. The metaldetector of claim 1, further comprising a first clamp diode having ananode connected to ground and a cathode connected to an output terminalto prevent the voltage at the capacitor from falling below ground. 3.The metal detector of claim 1, further comprising a second clamp diodehaving an anode connected to an output terminal and a cathode connectedto a reference voltage source to prevent the voltage at the capacitorfrom rising past a reference voltage.
 4. The metal detector of claim 1,wherein the controller detects the presence of the metallic surgicaldevice inside the hollow tube by determining a Q value from the decayingvoltage waveform.
 5. The metal detector of claim 1, wherein thecontroller determines the presence of the metallic surgical device bydetermining an average value of the waveform.
 6. The metal detector ofclaim 1, wherein the controller determines the presence of the metallicsurgical device by determining the peak value of at least one of thewaves in the decaying waveform.
 7. The metal detector of claim 1,wherein the controller determines the presence of the metallic surgicaldevice by determining times at which the waves in the decaying waveformcross a preselected voltage value.
 8. The metal detector of claim 1,wherein the controller determines the presence of the metallic surgicaldevice by determining a signal energy of the decaying waveform over apreselected time window.
 9. The metal detector of claim 8, wherein thecontroller determines the presence of the metallic surgical device bydetermining an integral of the decaying waveform over the preselectedtime window.
 10. The metal detector of claim 1, wherein the controllerdetermines a longitudinal position of the metallic surgical deviceinside the hollow tube from the decaying waveform.
 11. The metaldetector of claim 1, wherein the controller calibrates an initial Qvalue without any metal object in the hollow tube.
 12. A method ofdetecting insertion of a metallic surgical device into a hollow tube,comprising: connecting a power supply to a resonant circuit having acapacitor and an inductor mounted to the hollow tube, the inductor andthe capacitor connected in parallel to each other; disconnecting thepower supply from the resonant circuit after a preselected time periodto charge the capacitor to a selected initial voltage to generate adecaying waveform from the resonant circuit; detecting a presence of themetallic surgical device in the hollow tube based on the generateddecaying waveform; wherein the hollow tube is coupled to an end effectorof a robotic system, wherein when the metallic surgical instrument isdetected within the hollow tube, the controller prevents the endeffector from moving, thereby causing a trajectory and orientation ofthe metallic surgical device to be fixed through the hollow tube duringa surgical procedure.
 13. The method of claim 12, further comprisingclamping the decaying waveform to prevent the voltage of the decayingwaveform from falling below ground.
 14. The method of claim 12, furthercomprising clamping the decaying waveform to prevent the voltage of thedecaying waveform from rising past a reference voltage.
 15. The methodof claim 12, wherein the presence of the metallic surgical device insidethe hollow tube is detected by determining a Q value from the decayingvoltage waveform.
 16. The method of claim 12, wherein the presence ofthe metallic surgical device is determined by determining times at whichthe waves in the decaying waveform cross a preselected voltage value.17. The method of claim 12, wherein the presence of the metallicsurgical device is determined by determining an integral of the decayingwaveform over a preselected time window.
 18. The method of claim 12,wherein the controller determines a longitudinal position of themetallic surgical device inside the hollow tube from the decayingwaveform.
 19. The method of claim 12, further comprising calibrating aninitial Q value of the resonant circuit without any metal object in thehollow tube.